LONDON (Reuters) - The World Bank and World Health Organization have voiced fears that donor nations will slash health aid budgets because of the economic downturn, but experts said on Friday such a move could harm recovery prospects.

Researchers from Britain and the United States looked back over 30 years of economic ups and downs in Europe and found that most countries did not cut development funds during recessions. They said the findings suggest some governments may be using recession as a smokescreen for political decisions to cut aid.

"There isn't a simple one-to-one relationship where if a country faces economic problems then it cuts back on aid. If it does cut back, then it's doing so for ideological and political reasons," said Martin McKee of the European Centre on Health of Societies in Transition at the London School of Hygiene and Tropical Medicine.

Advocates for global health aid say it is critical for healthcare infrastructure development in poor countries and for sustaining existing health projects and starting new ones.

"There is a clear association between better health and economic growth, and if money given in development assistance is appropriately designed to improve health, then we can expect there will be a positive effect in terms of economic growth," McKee said in a telephone interview.

Last year, the United Nations Secretary-General Ban Ki-moon urged debt-ridden donor countries not to cut aid to the poor despite their budgetary difficulties.

In a report of their study, which was published in the Bulletin of the World Health Organization, McKee and colleagues said that according to 2009 reports of global aid budgets, Italy and Ireland have reduced development aid by 56 percent and 10 percent, respectively.

On the other hand, Britain has protected its aid budget from cuts and Australia, Germany, and the United States have all made commitments to increasing their support to protect vulnerable groups from the impact of the crisis, they said.

"It's no longer reasonable to think about far away countries of which we know little. We are interdependent and we need to consider the implications of that," McKee said.

The researchers analyzed data on health aid and economic downturns from 15 European Union (EU) countries covering the past three decades, from 1975 to 2007.

They found what they described as "surprisingly little" evidence that economic downturns are associated with deep cuts in aid, at least in the first few years of a financial crisis.

While some countries did reduce aid, they said, others increased it -- often in ways that did not seem to depend on the scale of the financial crisis they were facing.

David Stuckler, an assistant professor of political economy at the U.S. Harvard School of Public Health who also worked on the study, said the findings showed there were alternative ways of financing economic recovery.

"To achieve a sustainable economic recovery, governments must first take care of people's most basic health needs," he said in a statement.